THERE ARE plenty of restaurants along K Street NW in the stretch between Franklin Square and Washington Circle, some very good; but few are as consciously and even brashly idiosyncratic as Restaurant Kolumbia. And that's one key to its attraction.

Chef-owner Jamie Stachowski has played around in so many kitchens -- others' (Wolfgang Puck, Jean-Louis Palladin) and his own (J. Paul's, Pesce, eCitie) -- that he picks up a little from one style and then another. At the moment, the months he spent hanging out after buying Kolumbia's predecessor, the Middle Eastern Le Tarbouche, are showing nicely. He's an experimenter, and most of the time his curiosity serves him well, although even a fan of okra might remain unconvinced that its texture entirely complements the lobster-she crab bisque.

One of the most intriguing, and entirely successful, appetizers places lightly sauteed sweetbreads over a small salad of baby spinach studded with halved grapes, pine nuts and a nicely restrained scattering of tiny briny capers. Another is a tart filled with fresh, tangy anchovies and oven-dried tomatoes, something like the most extravagant reconstruction of a pizza one could imagine. (On the menu, however, the tart is paired with a merely dutiful tuna tartare, which it entirely overshadows.)

Stachowski can do classic, too, of course. While so many foie gras appetizers seem to lie, like Keats's poor knight, "alone and palely loitering," on the plate, his torchon is not only generously portioned but unusually complex in flavor, with a touch of sea salt and a ghostly hint of something like fine marrow or glace around the edges. A braised veal cheek was so tender it almost shivered away from the fork, and the reduction was elegantly viscous. (Grilling the accompanying slice of stuffed shoulder for "color," however, took its toll in tenderness.) Kijiki, a meaty Hawaiian marlin, was cooked through only to the exact point that erased any possible hint of mineral tang but did not harden the flesh.

There are many nice details here, not the least of which is passing mashed potatoes through a mesh so fine it feels like cream. Meals begin with an amuse, most recently an impressively crisp little cigarillo stuffed with spicy chicken, cut on the angle and balanced on a spoonful of shallot-topped remoulade. Good crusty bread comes with both butter and a fine eggplant spread. And although it's less obvious, Stachowski's attention to seasoning is equally meticulous: There is neither salt nor pepper on the table, and it's rarely wanted. The one exception might be the spinach salad, where a touch of freshly ground pepper added a sweet heat to the piquancy of the capers.

The lounge area is often busy, and with good reason. Not only are the booths along one side rather romantic, but the bar menu is an intriguing mix of snacks and light fare, available all afternoon: the anchovy tart and tartare, the spicy chicken samboussek with shallot sauce, the clams, even (skirt) steak and fries, at $15 the most expensive item. The real indulgence, on a bargain budget, would be the "flight bite," what Stachowski calls a "mini chef's tasting" of three courses paired with a traditional flight of three half-glasses of wine for $22.

The wine list in general is a nice change, not overly long or pretentious but smart, varied and, for the most part, moderately priced. That's thanks to Stachowski's wife and co-owner, Carolyn Stachowski, a certified sommelier and herself a veteran of Washington's restaurant scene. (Her list recently won Kolumbia kudos from Wine Spectator magazine.)

Kolumbia also reminds one why K Street is famous for expense account lunches, not because the restaurant is unduly pricey but because the choices are as provoking, in both senses, as at dinner: duck confit and galantine over fruit and chevre; grilled squid with arugula, kalamata olives, mint and fried lemons; lobster salad with papaya, avocado and brandade ravioli -- just to mention some of the salads.

There are occasions when the presentations are unnecessarily flashy: The lovely foie gras was oddly distracted, and the otherwise competent brioche made soggy, by a clashingly frivolous cherry foam. An appetizer listed as "warm clams ceviche 'casino' " is rather more casino than ceviche, since even the bare warming stiffens the clams somewhat. The ricotta gnocchi don't clash with the tiger shrimp, and both are deftly handled, but the two don't do much for each other, either.

Service alternates between attentive and erratic. Every once in a while, something goes missing. The promised homemade saltine crackers with the soup never arrived, and at least one night the gnocchi were plated without the tomato confit. Leftovers might be packed up without essential condiments -- tartar sauce for the fish and chips. And what's with the sudden craze for fish and chips, anyway? Just because a chef can make better and crisper flounder tenders than a fast-food joint doesn't mean he should. Pretty good fries, though. (Note that at press time, the menu was about to undergo a seasonal rewrite.)

Even after a couple of years, Kolumbia still seems to be in the process of discovery. But who said predictability was a virtue?

Restaurant Kolumbia's crispy sweetbreads, rear, and veal trio.